Cable networks are communication networks that communicate broadband communication signals between a centralized headend and a plurality of customer premise devices. Cable networks have many forms, but typically include a dispersed network of coaxial cable. Many cable networks further include a substantial portion of fiber optic lines. Such networks are known as hybrid fiber coax or HFC networks. Such networks are common.
Historically, cable networks were employed primarily for the delivery of the television program signals. To this end, the cable network headend transmitted a broadband signal to each subscriber through a hierarchical network of coaxial cable, referred to as the cable plant. The broadband signal was divided into a plurality of channels, each channel occupying an approximately 6 or 8 MHz wide band of the overall broadband signal.
The proper operation of cable systems involves field testing. Because the cable plant is dispersed throughout the entire cable service area, the network can experience damage or other detrimental phenomena in varied, isolated portions of the network. As a result, many customers may have excellent service while a few customers cannot receive one or more channels clearly due to a localized problem. Cable service providers have often used handheld signal measurement equipment to help diagnose problems and perform network analysis.
Historically, the test equipment included an RF signal receiver and circuitry for measuring signals received on select channels of the system. Measurement of a large number of channels provides a rough spectrum analysis of the cable network. Various test devices that measured analog cable television channels were developed.
While the cable television system employed analog NTCS standard television signals for years, cable service providers have more recently been switching over to digital television signal broadcasting because of the better cost/service ratios. Because many of the field test equipment developed for cable networks was specifically designed to test analog cable television channels, new digital cable field measurement technologies had to be developed. Such devices were developed, and typically measured the signal level available on selected (or all) channels of the cable television system.
The latest trend in cable systems is to provide two way high speed data communications through the cable network. A customer may thus use their coaxial cable connection to obtain both audio-visual broadcast programming information and for access to the Internet for electronic mail, downloads and browsing. The HFC network is further configured to support a specialized form of telephone service known as Voice over Internet Protocol or VoIP.
At present, signal level measurements and other related physical layer measurements still provide useful information in troubleshooting and analyzing network performance. However, there is a need for more extensive testing of the various services provided to the customer.